Chromous siloxides of variable nuclearity and magnetism.

Treatment of Cr[N(SiMe)](thf) with HOSiR (R = Et, Pr) in THF afforded the bridged Cr siloxide complexes Cr(OSiEt)(μ-OSiEt)(thf) and Cr(OSiPr)(μ-OSiPr)(thf) in high yield. Exposure of these compounds to vacuum in aliphatic solvents led to the loss of coordinated THF and to the formation of the homoleptic chromous siloxides Cr(μ-OSiEt) and Cr(OSiiPr)(μ-OSiPr), respectively, in moderate to high yield. Use of TMEDA as a potentially bidentate donor molecule gave the monomeric -coordinated siloxide Cr(OSiiPr)(tmeda) (tmeda = ,,','-tetramethylethane-1,2-diamine).

Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)-μ -Methylidyne Complex.

Reaction of CHI with six equivalents of CrCl in THF at low temperatures affords [Cr Cl (μ -Cl) (μ -CH)(thf) ] as the first isolable high-yield Cr μ -methylidyne complex. Substitution of the terminal chlorido ligands via salt metathesis with alkali-metal cyclopentadienides generates isostructural half-sandwich chromium(III)-μ -methylidynes [Cp Cr (μ -Cl) (μ -CH)] (Cp =C H , C Me , C H SiMe ). Side and decomposition products of the Cl/Cp exchange reactions were identified and structurally characterized for [Cr (μ -Cl) (μ -I) (μ -O)(thf) ] and [(η -C H SiMe )CrCl(μ -Cl) Li(thf) ].